/*
- * ChaCha20 256-bit cipher algorithm, RFC7539, ARM NEON functions
+ * ChaCha/XChaCha NEON helper functions
*
* Copyright (C) 2016 Linaro, Ltd. <ard.biesheuvel@linaro.org>
*
* (d) vtbl.8 + vtbl.8 (multiple of 8 bits rotations only,
* needs index vector)
*
- * ChaCha20 has 16, 12, 8, and 7-bit rotations. For the 12 and 7-bit
- * rotations, the only choices are (a) and (b). We use (a) since it takes
- * two-thirds the cycles of (b) on both Cortex-A7 and Cortex-A53.
+ * ChaCha has 16, 12, 8, and 7-bit rotations. For the 12 and 7-bit rotations,
+ * the only choices are (a) and (b). We use (a) since it takes two-thirds the
+ * cycles of (b) on both Cortex-A7 and Cortex-A53.
*
* For the 16-bit rotation, we use vrev32.16 since it's consistently fastest
* and doesn't need a temporary register.
.align 5
/*
- * chacha20_permute - permute one block
+ * chacha_permute - permute one block
*
* Permute one 64-byte block where the state matrix is stored in the four NEON
* registers q0-q3. It performs matrix operations on four words in parallel,
* but requires shuffling to rearrange the words after each round.
*
+ * The round count is given in r3.
+ *
* Clobbers: r3, ip, q4-q5
*/
-chacha20_permute:
+chacha_permute:
adr ip, .Lrol8_table
- mov r3, #10
vld1.8 {d10}, [ip, :64]
.Ldoubleround:
// x3 = shuffle32(x3, MASK(0, 3, 2, 1))
vext.8 q3, q3, q3, #4
- subs r3, r3, #1
+ subs r3, r3, #2
bne .Ldoubleround
bx lr
-ENDPROC(chacha20_permute)
+ENDPROC(chacha_permute)
-ENTRY(chacha20_block_xor_neon)
+ENTRY(chacha_block_xor_neon)
// r0: Input state matrix, s
// r1: 1 data block output, o
// r2: 1 data block input, i
+ // r3: nrounds
push {lr}
// x0..3 = s0..3
vmov q10, q2
vmov q11, q3
- bl chacha20_permute
+ bl chacha_permute
add ip, r2, #0x20
vld1.8 {q4-q5}, [r2]
vst1.8 {q2-q3}, [ip]
pop {pc}
-ENDPROC(chacha20_block_xor_neon)
+ENDPROC(chacha_block_xor_neon)
-ENTRY(hchacha20_block_neon)
+ENTRY(hchacha_block_neon)
// r0: Input state matrix, s
// r1: output (8 32-bit words)
+ // r2: nrounds
push {lr}
vld1.32 {q0-q1}, [r0]!
vld1.32 {q2-q3}, [r0]
- bl chacha20_permute
+ mov r3, r2
+ bl chacha_permute
vst1.32 {q0}, [r1]!
vst1.32 {q3}, [r1]
pop {pc}
-ENDPROC(hchacha20_block_neon)
+ENDPROC(hchacha_block_neon)
.align 4
.Lctrinc: .word 0, 1, 2, 3
.Lrol8_table: .byte 3, 0, 1, 2, 7, 4, 5, 6
.align 5
-ENTRY(chacha20_4block_xor_neon)
+ENTRY(chacha_4block_xor_neon)
push {r4-r5}
mov r4, sp // preserve the stack pointer
sub ip, sp, #0x20 // allocate a 32 byte buffer
// r0: Input state matrix, s
// r1: 4 data blocks output, o
// r2: 4 data blocks input, i
+ // r3: nrounds
//
- // This function encrypts four consecutive ChaCha20 blocks by loading
+ // This function encrypts four consecutive ChaCha blocks by loading
// the state matrix in NEON registers four times. The algorithm performs
// each operation on the corresponding word of each state matrix, hence
// requires no word shuffling. The words are re-interleaved before the
vdup.32 q0, d0[0]
adr ip, .Lrol8_table
- mov r3, #10
b 1f
.Ldoubleround4:
vsri.u32 q5, q8, #25
vsri.u32 q6, q9, #25
- subs r3, r3, #1
+ subs r3, r3, #2
bne .Ldoubleround4
// x0..7[0-3] are in q0-q7, x10..15[0-3] are in q10-q15.
pop {r4-r5}
bx lr
-ENDPROC(chacha20_4block_xor_neon)
+ENDPROC(chacha_4block_xor_neon)
#include <asm/neon.h>
#include <asm/simd.h>
-asmlinkage void chacha20_block_xor_neon(u32 *state, u8 *dst, const u8 *src);
-asmlinkage void chacha20_4block_xor_neon(u32 *state, u8 *dst, const u8 *src);
-asmlinkage void hchacha20_block_neon(const u32 *state, u32 *out);
-
-static void chacha20_doneon(u32 *state, u8 *dst, const u8 *src,
- unsigned int bytes)
+asmlinkage void chacha_block_xor_neon(const u32 *state, u8 *dst, const u8 *src,
+ int nrounds);
+asmlinkage void chacha_4block_xor_neon(const u32 *state, u8 *dst, const u8 *src,
+ int nrounds);
+asmlinkage void hchacha_block_neon(const u32 *state, u32 *out, int nrounds);
+
+static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
+ unsigned int bytes, int nrounds)
{
u8 buf[CHACHA_BLOCK_SIZE];
while (bytes >= CHACHA_BLOCK_SIZE * 4) {
- chacha20_4block_xor_neon(state, dst, src);
+ chacha_4block_xor_neon(state, dst, src, nrounds);
bytes -= CHACHA_BLOCK_SIZE * 4;
src += CHACHA_BLOCK_SIZE * 4;
dst += CHACHA_BLOCK_SIZE * 4;
state[12] += 4;
}
while (bytes >= CHACHA_BLOCK_SIZE) {
- chacha20_block_xor_neon(state, dst, src);
+ chacha_block_xor_neon(state, dst, src, nrounds);
bytes -= CHACHA_BLOCK_SIZE;
src += CHACHA_BLOCK_SIZE;
dst += CHACHA_BLOCK_SIZE;
}
if (bytes) {
memcpy(buf, src, bytes);
- chacha20_block_xor_neon(state, buf, buf);
+ chacha_block_xor_neon(state, buf, buf, nrounds);
memcpy(dst, buf, bytes);
}
}
-static int chacha20_neon_stream_xor(struct skcipher_request *req,
- struct chacha_ctx *ctx, u8 *iv)
+static int chacha_neon_stream_xor(struct skcipher_request *req,
+ struct chacha_ctx *ctx, u8 *iv)
{
struct skcipher_walk walk;
u32 state[16];
nbytes = round_down(nbytes, walk.stride);
kernel_neon_begin();
- chacha20_doneon(state, walk.dst.virt.addr, walk.src.virt.addr,
- nbytes);
+ chacha_doneon(state, walk.dst.virt.addr, walk.src.virt.addr,
+ nbytes, ctx->nrounds);
kernel_neon_end();
err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
}
return err;
}
-static int chacha20_neon(struct skcipher_request *req)
+static int chacha_neon(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
if (req->cryptlen <= CHACHA_BLOCK_SIZE || !may_use_simd())
return crypto_chacha_crypt(req);
- return chacha20_neon_stream_xor(req, ctx, req->iv);
+ return chacha_neon_stream_xor(req, ctx, req->iv);
}
-static int xchacha20_neon(struct skcipher_request *req)
+static int xchacha_neon(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
crypto_chacha_init(state, ctx, req->iv);
kernel_neon_begin();
- hchacha20_block_neon(state, subctx.key);
+ hchacha_block_neon(state, subctx.key, ctx->nrounds);
kernel_neon_end();
+ subctx.nrounds = ctx->nrounds;
memcpy(&real_iv[0], req->iv + 24, 8);
memcpy(&real_iv[8], req->iv + 16, 8);
- return chacha20_neon_stream_xor(req, &subctx, real_iv);
+ return chacha_neon_stream_xor(req, &subctx, real_iv);
}
static struct skcipher_alg algs[] = {
.chunksize = CHACHA_BLOCK_SIZE,
.walksize = 4 * CHACHA_BLOCK_SIZE,
.setkey = crypto_chacha20_setkey,
- .encrypt = chacha20_neon,
- .decrypt = chacha20_neon,
+ .encrypt = chacha_neon,
+ .decrypt = chacha_neon,
}, {
.base.cra_name = "xchacha20",
.base.cra_driver_name = "xchacha20-neon",
.chunksize = CHACHA_BLOCK_SIZE,
.walksize = 4 * CHACHA_BLOCK_SIZE,
.setkey = crypto_chacha20_setkey,
- .encrypt = xchacha20_neon,
- .decrypt = xchacha20_neon,
+ .encrypt = xchacha_neon,
+ .decrypt = xchacha_neon,
}
};
-static int __init chacha20_simd_mod_init(void)
+static int __init chacha_simd_mod_init(void)
{
if (!(elf_hwcap & HWCAP_NEON))
return -ENODEV;
return crypto_register_skciphers(algs, ARRAY_SIZE(algs));
}
-static void __exit chacha20_simd_mod_fini(void)
+static void __exit chacha_simd_mod_fini(void)
{
crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
}
-module_init(chacha20_simd_mod_init);
-module_exit(chacha20_simd_mod_fini);
+module_init(chacha_simd_mod_init);
+module_exit(chacha_simd_mod_fini);
+MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (NEON accelerated)");
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_CRYPTO("chacha20");
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